A custodian found the camera in one of two stalls in the ladies’ room, hidden behind a cracked wall tile next to a pipe connected to the toilet, sources said.

“Apparently, it had been there a month,” said Bulic, who did not join the lawsuit against the design center. “It’s not normal to look back there when you go to the bathroom.”

Seventeen other women who work in the building filed suit in Manhattan Supreme Court last week, charging New York Design Center with negligence. A judge permitted all except one to ­remain anonymous.

“This is a terrible invasion of privacy,” said their lawyer, Joel M. Rubenstein. “Our clients feel like they’ve been violated, as any woman or person would.”

The 16-story design center, called “an interior designer’s Disneyland,” is housed in an elegant complex built in 1926. It features 100 showrooms of furniture, fabrics, flooring, wall coverings, kitchen and bath appliances and decorative pieces.

“Our clientele is usually the high-end New York housewife who can afford to spend up to $4,000 or $5,000 on one of our items,” an employee said.

Of the bathroom breach, another female worker said, “You wouldn’t expect it from such a prestigious building.”

Shoppers were appalled.

“There are a lot of pathetic, desperate, dirty people out there,” one woman said.

The suit demands that the New York Design Center make “all reasonable efforts” to notify victims, locate images or video taken of women and have them destroyed after any criminal proceedings. It seeks unspecified compensatory and punitive damages.

An NYPD spokesman said detectives have an “open, active investigation.”

Phone and e-mail messages left with New York Design Center officials on Saturday were not returned.